package FloodFill;

import java.util.LinkedList;
import java.util.Queue;

public class NumIslands {
    int[] dx = new int[]{0, 0, 1, -1};
    int[] dy = new int[]{1, -1, 0, 0};
    boolean[][] vis = new boolean[301][301];
    int m, n;


    public int code(char[][] grid) {
        m = grid.length;
        n = grid[0].length;
        int ret = 0;


        for (int i = 0; i < m; i++){
            for (int j = 0; j < n; j++){
                if (grid[i][j] == '1' && vis[i][j] == false){
                    ret++;
                    bfs(grid, i, j);
                }
            }
        }

        return ret;
    }

    public void bfs(char[][] grid, int i, int j){
        Queue<int[]> q = new LinkedList<>();
        q.add(new int[]{i, j});
        vis[i][j] = true;

        while (!q.isEmpty()){
            int[] t = q.poll();

            for (int k = 0; k < 4; k++){
                int x = t[0] + dx[k], y = t[1] + dy[k];

                if (x >= 0 && x < m && y >= 0 && y < n && grid[x][y] == '1' && vis[x][y] == false){
                    vis[x][y] = true;
                    q.add(new int[]{x, y});
                }
            }

        }
    }

    public static void main(String[] args) {
        NumIslands test = new NumIslands();
        test.code(new char[][]{{'1','1', '0','0','0'},{'1','1','0','0','0'},
                {'0','0','1','0','0'},{'0','0','0','1','1'}});
    }
}
